Considerations on an automatic computed tomography tube current modulation system

Moro, Luca; Panizza, D.; D’Ambrosio, Daniela; Carne, Irene

doi:10.1093/rpd/nct095

Cited by 19 publications

(18 citation statements)

References 15 publications

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“…This is in accordance with one previous study 15 and contrary to another that found that the two were equivalent. 13 It is owing perhaps to the smaller projected area of the CT table, although it has also been suggested that the greater magnification of the spine in the PA view plays a role.…”

Section: Discussionsupporting

confidence: 93%

“…13 It is owing perhaps to the smaller projected area of the CT table, although it has also been suggested that the greater magnification of the spine in the PA view plays a role. 15 The 90°localizer angle was found to offer lower radiation output than did both 0°and 180°localizer angles. Again there is no consensus among previous research for this finding, with studies that both corroborate it 12,13 and find the contrary.…”

Section: Discussionmentioning

confidence: 88%

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Investigating the CT localizer radiograph: acquisition parameters, patient centring and their combined influence on radiation dose

Lambert

Kumar²,

Chen³

et al. 2015

BJR

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Objective: To systematically investigate the effect of CT localizer radiograph acquisition on the tube current modulation and thus radiation dose of the subsequent diagnostic scan. Methods: Localizer radiographs of an abdominal section CT phantom were taken, and the resulting volume CT dose index (CTDIvol) for the diagnostic scan was recorded. Variables included tube potential, the phantom's alignment within the CT scanner gantry in both the vertical and horizontal directions and the X-ray source angle at which the localizer was acquired. Results: Diagnostic scan CTDIvol decreased with increasing tube potential. Vertical (table height) movement was found to affect radiation dose more than horizontal movement, with 650 mm table movement resulting in a standard deviation in the diagnostic scan CTDIvol of 4.4 mGy, compared with 2.5 mGy with 6 50 mm horizontal movement. Correspondingly, localizer angles of 90°or 270°(3 o'clock and 9 o'clock X-ray source positions) were less sensitive overall to alignment errors, with a standard deviation of 2.5 mGy, compared with a 0°or 180°angle, which had a standard deviation of 3.8 mGy. Conclusion: To achieve a consistently optimized radiation dose, the localizer protocol should be paired with the diagnostic acquisition protocol. A final acquisition angle of 90°should be used when possible to minimize dose variation resulting from alignment errors. Advances in knowledge: Localizer parameters that affect radiation output were identified for this scanner system. The importance of tube potential and acquisition angle was highlighted.Radiation exposure from medical imaging remains in the public awareness and has spurred the adoption of several technologies to minimize CT dose.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 88%

Investigating the CT localizer radiograph: acquisition parameters, patient centring and their combined influence on radiation dose

Lambert

Kumar²,

Chen³

et al. 2015

BJR

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“…The way certain scan settings affect the ATCM from different vendors has been an area of interest for many years. 3,[5][6][7][8][9][10][11][12] The focus has been on the effect of a limited number of scan settings or on a specific vendor ATCM. However, an extensive study investigating the influence of all variable scan settings and covering all of the vendor implementations of ATCM is, to our knowledge, missing in the literature.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the impact of scan settings on automatic tube current modulation in CT using a novel phantom

Merzan¹,

Nowik²,

Poludniowski³

et al. 2017

BJR

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Objective: The aim of this study was to make a comprehensive evaluation of how variable scan settings can affect the performance of automatic tube current modulation (ATCM) in recent CT scanners from the four major manufacturers. Methods: A phantom was designed and manufactured for the purpose of evaluating ATCM. The phantom was scanned with four categories of systematically varied settings (scan projection radiograph, technique and reconstruction parameters and phantom miscentring). The performance of ATCM, in terms of applied tube current and noise uniformity, for the scans with varied settings was compared with a reference scan using subjective and quantitative approaches. Results: The ATCM implemented by each manufacturer is based on different principles and any affect to the performance of the ATCM, when varying scan settings, will manifest differently among the vendors. The results are summarized in four tables corresponding to the categories of varied settings. Conclusion: The developed phantom proved useful for evaluating the ATCM. It is important to understand how different implementations (vendor specific) of ATCM perform in order to make informed decisions about the selection of scan settings when designing protocols. The resulting tables can serve as a reference for understanding the different implementations of ATCM and highlight settings that should be taken into consideration when adjusting an imaging protocol. Advances in knowledge:The results from this work can serve as a reference for how changes in geometry or scan settings can affect the performance of ATCM, in terms of tube current and noise.

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“…The results showed that at noise index values of 18-25 HU, the quality of CT images sufficed for diagnostic purposes in abdomen [17,18]. Moro et al reported that the range of noise indexed in chest was 10 to 25 HU [19]. Therefore, in the current study, the noise index values were chosen as either 21 HU, the default value of the scanner, or 25 HU, the upper limit reported in literature.…”

Section: Aecmentioning

confidence: 89%

Reduction of radiation dose in the spiral CT scan of the lumbar spine by the combined use of body mass index (BMI) and automatic exposure control (AEC)

Tan

Zhan

Yang

et al. 2014

Journal of X-Ray Science and Technology

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OBJECTIVE: The aim of this study was to investigate the significance of the combined use of BMI and AEC in reducing the radiation dose of CT volume scans of the lumbar spine. METHODS: A prospective study was performed to continuously collect data from 50 patients (age range from 19 to 60 years, male versus female 20/30) whose BMIs were less than 25 kg/m 2 (group A) and 50 patients (age range from 21 to 82 years, male versus female 24/26) whose BMIs were equal to or more than 25 kg/m 2 (group B). The 50 patients in each group were randomly divided into 5 subgroups with each subgroup having lower radiation dose from subgroup 1 to 5. All the patients were performed lumbar spiral CT scans (GE LightSpeed VCT 64-slice scanner) and the scan parameters were different in different subgroups. Volume CT dose index (CTDIvol) was recorded. The qualities of the images were graded. The one-way ANOVA and Kruskal-Wallis test were done. RESULTS: Both in group A and B, there were significant differences in CTDIvol among the 5 subgroups (P < 0.001). The quality of the images in the 5 subgroups of group A didn't show statistical difference. The standard deviation (SD) and signal to noise ratio (SNR) values of the L4-5 psoas major muscles in subgroup 5 of group B was statistical different from the other 4 subgroups (P < 0.01). CONCLUSION: Use of BMI combined with AEC reduces radiation dosage, without compromising the image quality. For patients in group A and group B, parameters of subgroup 5 and subgroup 4 may respectively be applied for lower dose CT scanning. W. Tan et al. / Reduction of radiation dose in the spiral CT scan of the lumbar spine by the combined Key pointsCT scan with lower X-ray dosage Lumbar spine disc CT scan combined with BMI and AEC BMI related parameters meet the goal of lowering radiation Abbreviations BMI = body mass index; AEC = automatic exposure control; CTDIvol = volume CT dose index; SD = standard deviation; SNR = signal to noise ratio; VR = volume rendering; ROI = region of interest; SSDE = size-specifc dose estimate; LSD = least significance difference; FBP = filtered back projection; ASIR = adaptive statistical iterative reconstruction; ATCM = automatic tube current modulation.

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Considerations on an automatic computed tomography tube current modulation system

Cited by 19 publications

References 15 publications

Investigating the CT localizer radiograph: acquisition parameters, patient centring and their combined influence on radiation dose

Investigating the CT localizer radiograph: acquisition parameters, patient centring and their combined influence on radiation dose

Evaluating the impact of scan settings on automatic tube current modulation in CT using a novel phantom

Reduction of radiation dose in the spiral CT scan of the lumbar spine by the combined use of body mass index (BMI) and automatic exposure control (AEC)

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